The importance of intraocular lens inspection prior to implantation

Open-loop, posterior chamber intraocular lenses were obtained from existing inventories of regional hospitals and surveyed for functional (optical) and structural defects. The majority of lenses (90%) were acceptable by industry optical grade standards. Most of the lenses (90%) varied by at least 0.5 diopter from the power stated on the packaging. Two lenses did not meet optical resolution standards. Most of the lenses (80%) had some surface or loop surface abnormality as judged by scanning electron microscopy. Four of the lenses had surface protrusions or burrs, either at the tip of the loop or at the lens-optic junction. These more serious defects could be seen easily at magnifications of the operating microscope. The lenses with serious structural defects tended to be the same as those lenses with functional (optical) defects. This study demonstrates the usefulness of careful intraoperative examination using the operating microscope prior to intraocular lens implantation to detect manufacturing defects which continue to exist in currently manufactured lenses. Lens inspection should be directed to the ends of the loops, the loop-optic junction, and the internal surface of the positioning holes.